The present invention relates to the catalytic isomerization of allylic alcohols to saturated ketones and more particularly to the catalyzed isomerization of a beta-, gamma-unsaturated cycloalkenol to a saturated cycloalkanone.
In pure form, the instant cycloalkenols can be readily isomerized with copper chromite to their corresponding saturated cycloalkanones. However, various methods of making the cycloalkenols have residual acid-forming moieties contaminating the cycloalkenol. For example, one convenient method of preparing a cycloalkenol is described in U.S. Pat. No. 3,076,839. Normally, this process will leave impurities including organic halides and carboxylic acid esters. Such impurities can react under the influence of heat or isomerization catalysts to generate acids such as carboxylic acids, mineral acid, or Lewis acids. Such acidic moieties, even in trace amounts, can cause dehydration or isomerization of the alkenols under isomerization conditions, thereby substantially reducing the yield of the desired cycloalkanone.
The instant invention provides a method for suppressing the adverse effects which the acid-forming moiety contaminating the cycloalkenol would otherwise display during the isomerization process. In a preferred embodiment of the present invention, the instant isomerization process is an important step in a new synthesis of dl-method.